Mark Zuckerberg gave an impassioned opening speech at Facebook's F8 developer conference keynote today, lambasting Republican presidential candidate Donald Trump and his supporters for cultivating a culture of fear in the US. Though he did not name Trump directly, Zuckerberg referenced the candidate's position on immigration and the infamous call to build a wall between the US and Mexico. The Facebook CEO says fighting against this mentality is an integral part of his company's 10-year roadmap.

As I look around and I travel around the world, I'm starting to see people and nations turning inward, against this idea of a connected world and a global community. I hear fearful voices calling for building walls and distancing people they label as others. For blocking free expression, for slowing immigration, reducing trade, and in some cases around the world even cutting access to the internet.

Of course, Zuckerberg wasn't just taking aim at Trump. He was calling out oppressive regimes who crack down on social networking tools like Facebook, and governments who wield access to the internet as a weapon against dissidents. Yet his comments about the current atmosphere surrounding the US presidential race were the most pointed. It was quite clear in these first few minutes whom the executive was speaking about without naming names.

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Donald Trump (l) and Mark Zuckerberg (r).

"It takes courage to choose hope over fear," Zuckerberg said. "People will always call you naive but it's this hope and this optimism thats behind every important step forward."